G-Protein-coupled Receptor 49 (GPR49), also known as LGR5/HG38/FEX, belongs to the leucine-rich repeat containing G-protein-coupled receptors (LGRs) structurally similar to glycoprotein hormone receptors. LGRs are divided into three subgroups: (1) glycoprotein hormone receptors including thyroid-stimulating hormone (TSH) receptor, follicle-stimulating hormone (FSH) receptor, and luteinizing hormone (LH) receptor; (2) relaxin receptors LGR7 and LGR8; and (3) GPR48, GPR49, and LGR6. GPR49 is expressed in several tissues including the intestine, skeletal muscle, placenta, brain, and spinal cord. However, little is known about the function of GPR49.